Interfaces vs. Classes: When Should You Choose Interfaces for Polymorphism and Loose Coupling?

Interfaces and classes: Why use interfaces?

In object-oriented programming, there is often a debate about whether to use an interface or an abstract class when defining a contract. Classes provide inheritance and method implementation, while interfaces only focus on declaring behavior.

Advantages of interface

Interfaces are mainly used in the following situations:

• Define and share common behaviors among multiple unrelated classes to achieve polymorphism.
• Isolate code from implementation details, create loose coupling and enhance scalability.
• Define a contract for the client without specifying a specific implementation.

Example: Using interfaces to achieve polymorphism

Consider the following code example:

<code>public interface ILogInterface
{
    void WriteLog();
}

public class MyClass : ILogInterface
{
    public void WriteLog()
    {
        // 我的自定义日志记录实现
    }
}

public class MyOtherClass : ILogInterface
{
    public void WriteLog()
    {
        // 我的自定义和不同的日志记录实现
    }
}

public class LogManager
{
    public void Log(IlogInterface log)
    {
        // 接受并调用实现 ILogInterface 的任何对象上的 WriteLog()，允许动态绑定。
        log.WriteLog();
    }
}</code>

In this example, we define an interface ILogInterface that specifies a WriteLog() method. MyClass and MyOtherClass implement this interface, but provide their own implementation of WriteLog(). LogManager can then accept and call ILogInterface on any object that implements WriteLog(), enabling logging from different sources with different behavior.

Why not implement the method directly in the class?

Implementing methods directly in the class simplifies the code, but it also tightly couples the client code to the implementation. If you later decide to change the implementation, all client code references will need to be searched and modified. Interfaces provide loose coupling, allowing you to add or change implementations without affecting client code.

The above is the detailed content of Interfaces vs. Classes: When Should You Choose Interfaces for Polymorphism and Loose Coupling?. For more information, please follow other related articles on the PHP Chinese website!